Bellwether Men's Thermaldress Tights (Black) (S) (No Chamois)

This is going to be lengthy, and hopefully quite informative:
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The medium size tights run way too small. I will give you my body statistics: I am considered to be a "thin person", and at 78 years old I am considered elderly, as well as being a highly experienced cyclist for the last 30 years. I have since shrunk down to 5'11", my waist size is 33", my weight is 152#, and basically at my age, my butt is almost non-existent. Also, my BMI (body mass index) is quite low being low 21%. These medium size tights wouldn't even get over my very thin thighs. I said to myself,, "OK, corporate things are never perfect", so I paid to return these tights and ordered the same tights in size LARGE,,, yes, you guessed correctly,, size large is still way too small. I then decided to wait on the return for the size large, and I then ordered the same tights in size XL (yes this is definitely on the outside of being ridiculous). When I receive the size XL I will add a second review.
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Below is my continuous review (08/25/23):
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Finally, after individually ordering size Medium & size Large, To date (08/25/23) both are currently under the return process. As the story goes, on 8/21/23 I ordered a size XL and this finally fits my medium-size BMI index #21 body. Hopefully, this 2nd review will keep someone from going through the return two of pairs of tights and having to pay appx $20 to return these first two purchases. The bottom line is I have to rate their sizing scale a low ONE STAR (*). However, I do have to add, aside from their fitting process being way OFF-SCALE I do have to admit my that my final XL size purchase looks & feels like a super-high-quality, pair of winter-lined tights (w/no chamois). I therefore gave this final XL size purchase 4 stars (it would have been 5 Stars but I have yet to actually use these during these upcoming winter months.

I have a similar pair that have served me well for more than ten years down to 32 degrees F while commuting and exercising (ten years ago they served me well down to 22 degrees F, but I've aged ten years). Now, there are two holes worm through in the butt. My question, perhaps toa Bellwether or Performance Rep, is whether these "new" tights have a similar amount of insulation, or less, or more?